From: Sean Wang <sean.wang@mediatek.com>

In order to open up the required power gate before any operation can be
effectively performed over the serial bus between CPU and serdev, it's
clearly essential to add common attach functions for PM domains to serdev
at the probe phase.

Similarly, the relevant dettach function for the PM domains should be
properly and reversely added at the remove phase.

Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Ulf Hansson <redacted>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <redacted>
Cc: linux-serial at vger.kernel.org
---
 drivers/tty/serdev/core.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
index df93b72..c93d8ee 100644
--- a/drivers/tty/serdev/core.c
+++ b/drivers/tty/serdev/core.c

@@ -13,6 +13,7 @@
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
+#include <linux/pm_domain.h>
 #include <linux/serdev.h>
 #include <linux/slab.h>

@@ -330,8 +331,16 @@ EXPORT_SYMBOL_GPL(serdev_device_set_tiocm);
 static int serdev_drv_probe(struct device *dev)
 {
        const struct serdev_device_driver *sdrv = to_serdev_device_driver(dev->driver);
+       int ret;
+
+       ret = dev_pm_domain_attach(dev, true);
+       if (ret != -EPROBE_DEFER) {

+               ret = sdrv->probe(to_serdev_device(dev));
+               if (ret)
+                       dev_pm_domain_detach(dev, true);
+       }

-       return sdrv->probe(to_serdev_device(dev));
+       return ret;
 }

 static int serdev_drv_remove(struct device *dev)

@@ -339,6 +348,9 @@ static int serdev_drv_remove(struct device *dev)
        const struct serdev_device_driver *sdrv = to_serdev_device_driver(dev->driver);
        if (sdrv->remove)
                sdrv->remove(to_serdev_device(dev));
+
+       dev_pm_domain_detach(dev, true);
+
        return 0;
 }

--

2.7.4